You should not need any sway control under normal conditions. Yes, it's good to have sway control for those non-normal conditions (i.e. bad weather, emergency lane changes) but if you have sway under normal conditions, you really should try to fix that first.
Have you weighed it? Too much tongue weight can be bad too, as that still allows the load center to induce yaw moments (steering forces) on the tow vehicle. Are your tire pressures adjusted for your actual load? Instead of adding weight towards the front, can you remove weight from the rear of the trailer (spare tire maybe?)? The closer the mass is to the trailer axles, the better it will tow. That's why boats tow so well even with only 5-8% tongue weight.
